1. Field of the Invention
The present invention relates in general to a pressure discharge valve for storage tanks containing petroleum products, acid, liquefied gases, and other flammable liquids and, more particularly, to a pressure discharge valve comprised of a eutectic composition designed to automatically vent when the contents of the storage tank reaches a predetermined dangerous temperature lower than a critical vent temperature.
2. Description of the Related Art
In general, storage tanks such as fuel tanks have operating temperatures between −60° F. to 160° F. In case of a fire, the temperature of the storage tank(s) rises beyond a safe operating temperature of, for example, 160° F., and the liquid contained inside the tank expands and creates an internal pressure (Hoop Pressure). At a certain point, as the internal pressure increases, the tank ruptures and creates a high order explosion.
If this hoop pressure were to be relieved, the high order explosion can be reduced to a low order reaction. These storage tanks can contain fuel oil, acid, liquefied gases and other types of materials that have a flash point, detonation or volatile ignition temperature that makes them unsafe for firefighters. A low order reaction still has a flame and fire associated with it, but it does not explode. By eliminating the explosion characteristic of storage tanks, firefighters can more effectively extinguish fires.
Conventional pressure relief valves typically vent the contents of a fuel tank when the pressure in the tank reaches a critical condition. However, conventional pressure relief valves do not provide a warning to firefighters as to when a burning storage tank is in a critical and an unsafe mode for firefighting efforts.
It is therefore an object of the present invention to provide a pressure discharge valve for storage tanks containing flammable and/or explosive liquids having a valve which automatically opens and vents said liquids before the temperature and/or pressure in the tank causes the tank to rupture, and/or resulting in a high order detonation.
It is another object of the present invention to provide a pressure discharge valve which minimizes and/or eliminates high order detonations of fuel tanks.
It is still another object of the present invention to provide a pressure discharge valve for fuel storage tanks which provides a signal to firefighters of an unsafe condition of the fuel storage tank.
It is yet another object of the present invention to provide a pressure discharge valve which will warn firefighters that the storage tank has reached a critical condition, and that rupture and/or detonation thereof may be imminent.